Financial Instruments - Schedule of marketable securities (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jul. 31, 2022	Jul. 31, 2021	Jul. 31, 2022	Jul. 31, 2021
Investments, All Other Investments [Abstract]
Marketable debt securities	$ 43	$ 0	$ 245	$ 4

The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities (held-to-maturity or available-for-sale) during the period.

No definition available.

Name:	us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration